202 lines
4.4 KiB
Markdown
202 lines
4.4 KiB
Markdown
# PostCSS Dir Pseudo Class [<img src="https://postcss.github.io/postcss/logo.svg" alt="PostCSS Logo" width="90" height="90" align="right">][PostCSS]
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[<img alt="npm version" src="https://img.shields.io/npm/v/postcss-dir-pseudo-class.svg" height="20">][npm-url] [<img alt="CSS Standard Status" src="https://cssdb.org/images/badges/dir-pseudo-class.svg" height="20">][css-url] [<img alt="Build Status" src="https://github.com/csstools/postcss-plugins/workflows/test/badge.svg" height="20">][cli-url] [<img alt="Discord" src="https://shields.io/badge/Discord-5865F2?logo=discord&logoColor=white">][discord]
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[PostCSS Dir Pseudo Class] lets you style by directionality using the `:dir()`
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pseudo-class in CSS, following the [Selectors] specification.
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```pcss
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article h3:dir(rtl) {
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margin-right: 10px;
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}
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article h3:dir(ltr) {
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margin-left: 10px;
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}
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/* becomes */
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[dir="rtl"] article h3 {
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margin-right: 10px;
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}
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[dir="ltr"] article h3 {
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margin-left: 10px;
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}
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```
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### Maintaining Specificity
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Using [PostCSS Dir Pseudo Class] will not impact selector weight, but it will
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require having at least one `[dir]` attribute in your HTML. If you don’t have
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_any_ `[dir]` attributes, consider using the following JavaScript:
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```js
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// force at least one dir attribute (this can run at any time)
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document.documentElement.dir=document.documentElement.dir||'ltr';
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```
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If you absolutely cannot add a `[dir]` attribute in your HTML or even force one
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via JavaScript, you can still work around this by presuming a direction in your
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CSS using the [`dir` option](#dir), but understand that this will
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sometimes increase selector weight by one element (`html`).
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## Usage
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Add [PostCSS Dir Pseudo Class] to your project:
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```bash
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npm install postcss postcss-dir-pseudo-class --save-dev
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```
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Use it as a [PostCSS] plugin:
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```js
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const postcss = require('postcss');
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const postcssDirPseudoClass = require('postcss-dir-pseudo-class');
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postcss([
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postcssDirPseudoClass(/* pluginOptions */)
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]).process(YOUR_CSS /*, processOptions */);
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```
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[PostCSS Dir Pseudo Class] runs in all Node environments, with special
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instructions for:
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- [Node](INSTALL.md#node)
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- [PostCSS CLI](INSTALL.md#postcss-cli)
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- [PostCSS Load Config](INSTALL.md#postcss-load-config)
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- [Webpack](INSTALL.md#webpack)
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- [Next.js](INSTALL.md#nextjs)
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- [Gulp](INSTALL.md#gulp)
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- [Grunt](INSTALL.md#grunt)
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## Options
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### preserve
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The `preserve` option determines whether the original notation
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is preserved. By default, it is not preserved.
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```js
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postcssDirPseudoClass({ preserve: true })
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```
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```pcss
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article h3:dir(rtl) {
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margin-right: 10px;
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}
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article h3:dir(ltr) {
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margin-left: 10px;
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}
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/* becomes */
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[dir="rtl"] article h3 {
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margin-right: 10px;
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}
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article h3:dir(rtl) {
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margin-right: 10px;
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}
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[dir="ltr"] article h3 {
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margin-left: 10px;
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}
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article h3:dir(ltr) {
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margin-left: 10px;
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}
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```
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### dir
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The `dir` option allows you presume a direction in your CSS. By default, this
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is not specified and you are required to include a direction `[dir]` attribute
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somewhere in your HTML, preferably on the `html` element.
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```js
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postcssDirPseudoClass({ dir: 'ltr' });
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```
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```pcss
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article h3:dir(rtl) {
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margin-right: 10px;
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}
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article h3:dir(ltr) {
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margin-left: 10px;
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}
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/* becomes */
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[dir="rtl"] article h3 {
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margin-right: 10px;
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}
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html:not([dir="rtl"]) article h3 {
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margin-left: 10px;
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}
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```
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```js
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postcssDirPseudoClass({ dir: 'rtl' });
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```
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```pcss
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article h3:dir(rtl) {
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margin-right: 10px;
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}
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article h3:dir(ltr) {
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margin-left: 10px;
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}
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/* becomes */
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html:not([dir="ltr"]) article h3 {
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margin-right: 10px;
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}
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[dir="ltr"] article h3 {
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margin-left: 10px;
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}
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```
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### shadow
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The `shadow` option determines whether the CSS is assumed to be used in Shadow DOM with Custom Elements.
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```js
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postcssDirPseudoClass({ shadow: true })
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```
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```pcss
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article h3:dir(rtl) {
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margin-right: 10px;
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}
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article h3:dir(ltr) {
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margin-left: 10px;
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}
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/* becomes */
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:host-context([dir="rtl"]) article h3 {
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margin-right: 10px;
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}
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:host-context([dir="ltr"]) article h3 {
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margin-left: 10px;
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}
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```
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[cli-url]: https://github.com/csstools/postcss-plugins/actions/workflows/test.yml?query=workflow/test
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[css-url]: https://cssdb.org/#dir-pseudo-class
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[discord]: https://discord.gg/bUadyRwkJS
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[npm-url]: https://www.npmjs.com/package/postcss-dir-pseudo-class
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[PostCSS]: https://github.com/postcss/postcss
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[PostCSS Dir Pseudo Class]: https://github.com/csstools/postcss-plugins/tree/main/plugins/postcss-dir-pseudo-class
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[Selectors]: https://www.w3.org/TR/selectors-4/#the-dir-pseudo
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